When the Harry Potter books were first released, Dumbledore seemed like a very benevolent and good mentor character in the first few years Harry was at Hogwarts. However, the final book revealed that Dumbledore was a much more complex character than he seemed with a rather dark past. While Dumbledore might still have wanted good things for the world, he wasn’t always ethical, and he made some huge mistakes.
Because of Dumbeldore’s power and influence in the wizarding world, many of his choices had far-reaching impacts and consequences on other people. And, while he didn’t always mean to do harm, he did still make some bad choices.
Leaving Harry with the Dursleys
This is one choice Dumbledore made that he might have meant with good intent, but it’s still rather messed up when you analyze it.
While Dumbledore wants Harry to have magical protection from Voldemort, he also chooses to have him live with abusive guardians where he was cut off from any kindness or support. He was neglected and treated horribly, and Harry’s trauma doesn’t get talked about enough.
Keeping his distance from Harry in Order of the Phoenix
A lot of Dumbledore's worst choices have to do with Harry and how he treated him. Given how much responsibility he placed on Harry and the burden he knew Harry carried, he definitely wasn't always there for him as he should have been. While he might have ignored Harry in an attempt to keep him safe from Voldemort, this just backfired.
Harry was going through a lot of things, and he needed Dumbledore’s support. Maybe with his help, Sirius wouldn’t have ended up dead.
He let horrible things happen at Hogwarts
While Dumbledore at first might have seemed like someone you’d want as your Headmaster or leader at school, he really wasn’t good at his job. He was supposed to be in charge of protecting the school and its students, but he was always gone when the school needed him most.
Given how much Dumbledore always seems to know, it seems strange he would abandon the school at so many points.
Letting Snape kill him
This is a bit of a complicated point because it can also be argued that Dumbledore made the right decision here. He was trying to save Draco which was a very admirable goal, but by saving Draco and sacrificing himself, he was also leaving Harry alone to fight Voldemort.
Without Dumbledore, things could have gone much worse for Harry, and Voldemort might never have been defeated. But, at the same time, it was a moral dilemma.
Not doing much about the Chamber of Secrets
This is a specific example of a way in which Dumbledore didn’t protect the students as he should have. Given that he was a professor when Moaning Myrtle was killed by Slytherin’s monster, he should have known the risks and shut down the school immediately.
He was reckless and careless to leave Hogwarts open while students were being attacked, and this led to Ginny being taken into the Chamber of Secrets.
Not telling Harry that he himself was a Horcrux
Dumbledore was always keeping information from Harry until he thought he was old enough. While he might have made excuses for this, given all of the things Harry had accomplished and all Dumbeldore expected of him, this was unacceptable.
Even after finally telling Harry the truth of the prophecy and Horcruxes, he still didn’t tell Harry that he suspected Harry was one, too. This made it so Harry had to figure this out on his own.
Not taking responsibility for his part in Ariana’s death
While Dumbledore made some pretty glaring mistakes during Harry’s time at school, he made some even worse ones when he was younger. His involvement with Grindelwald and the Dark Arts lead in some way to his sister’s death.
And, while privately he might have taken responsibility for this, he never talked about it or really claimed these mistakes publicly. This makes him seem sneaky and manipulative.
Not stopping Grindelwald sooner
While Dumbeldore being involved with Grindelwald and his hateful, anti-Muggle rhetoric was bad enough, his decision to wait to stop him might have been even worse.
He knew he was the only one who could really stop him, but he let innocent people be harmed because of her feelings for Grindelwald. This was a huge mistake that changed many other people’s lives.
Hiring so many unsafe professors
Given that Dumbeldore is so smart and powerful as a wizard, it’s amazing that he’s such a poor judge of character. While he did hire some good professors like Lupin, he also hired people like Lockhart and Quirrell.
And, on top of that, he also let professors like Snape continually abuse and bully their students with no repercussions.
Expecting Harry to do so much alone
Given that Harry is the protagonist of the story and that it’s a series meant for children, Harry does way more things than any teenager would really be expected to do.
However, even while allowing for some suspension of disbelief, it’s hard to justify how much Dumbledore let Harry do alone. He could have offered a lot more hands-on help either through himself or through the help of other adults.